With a balanced connection between cartridge and phono input, I have never had hum and I never noticed any sonic degradation from using shielded cables (which I routinely do use). These could both be virtues of the balanced connection to a balanced phono. However, I recently purchased an SE phono-only stage to use with MM/MI cartridges. Despite the fact that the SE cables between the tonearm and the phono stage are shielded, I have had to ground the tonearm to the phono stage externally, to eliminate a nasty hum. Real "hum" (60 to 120Hz tone or buzz) is typically due to a ground loop somewhere or to the proximity of an AC line or PS umbilical cord to an unshielded pair of ICs. I have had both issues with SE connections. Audioquest, you may want to look into these kinds of issues. Have you grounded the phono stage to the tonearm, for example?
